Shark toothとは 意味・読み方・使い方

Shark teeth are relics of shark evolution and biology, and as they are often the only part of the shark to survive fossilisation, represent much of the Selachimorpha fossil record, extending back hundreds of millions of years. The most ancient types of sharks date back to 450 million years ago during the Late Ordovician period, and they are mostly known from their fossilised teeth. The most common, however, are from the Cenozoic (65 million years ago). Sharks continually shed their teeth, and some Carcharhiniformes can shed approximately 35,000 teeth in a lifetime.